Third Time No Charm for Bulls

Major averages slipped Monday despite a 4% drop in the price of oil and a 6% drop in natural gas futures. The Dow ended the day down 0.2% to 12,552.55, and is now down 0.9% over the past three trading days. The S&P 500 closed down 0.3% Monday, and 1.1% over the past three days. The Nasdaq Composite fell 0.4% Monday and is off 1.6% since last Wednesday's close.

Energy companies fell along with the price of oil. Exxon Mobil (XOM Quote) slipped 0.8%, whileBP(BP Quote) and Chevron(CVX Quote) fell more than 1% apiece on the day.

News out of the biotech and health care sectors was mixed. Onyx Pharmaceuticals(ONXX Quote) surged 97% on news the company was successful in a trial for cancer drug Nexavar to treat liver cancer patients.

On the flip side, shares of Bristol-Myers Squibb(BMY Quote) slid 3.3% on news the company's merger talks with Sanofi-Aventis(SNY Quote) may have gone sour.

Concerns about housing bled into this week, as the selloff in the REIT sector continued. The selling was sparked when investors called a top for the sector after private-equity firm Blackstone Group agreed last week to buy Equity Office Properties(EOP Quote) after a heated bidding war.

Shares of S.L. Green Realty(SLG Quote) fell 2.9%, as did shares of Maguire Properties(MPG Quote) and General Growth Properties(GGP Quote).

Calling tops is something many strategists are trying to do these days. Jeffrey Saut, chief investment strategist at Raymond James, opens his Monday research note with the quote from Jack Nicholson's movie character Melvin Udall: "What if this is as good as it gets?"